The Yellow Quarantine Flag or “Q” Flag, is the universal Q letter in the International signal alphabet.
It is flown alone from a vessel to indicate that there is no disease aboard and to request pratique or, with a second signal flag (usually a white flag), to indicate that there is disease on board.
Yellow Quarantine Flag is available in two sizes: 12 x 18 inches and 16 x 24 inches.
You can fly them on your boat or Just hang them in your home!